Studies reveal brain cortex differences

Children with autism have more of the cortex buried within the surface of the brain, two studies show.

Professor Ralph Axel-Müller, of San Diego State University, led one of the groups. His scientists examined MRI data from 64 children and adults with autism, as well as 64 typically developing peers aged seven to 19.

Professor Ralph Axel-Müller says genetic and environmental factors may play a role in folding found in autistic children’s brains

They found parts of the cortex folded or buried in three of the four main lobes of the brain.

Brain folding decreased with age

However, they discovered that the folding decreased with age in both autistic and typically developing children.

The researchers also looked at an independent sample of 31 autistic children from the Autism Brain Imaging Data Exchange and 31 typically developing children.

They found it confirmed the findings from the first group, though the folding was less extensive.

Folding relates to ‘brain overgrowth’

In an email, Axel-Müller said they believe the folding relates to early “brain overgrowth”.

He said genetics are “involved” in severe brain overgrowth. He added that environmental factors may also play a part during pregnancy.

Dr Christine Nordahl, associate professor of psychiatry and behavioral sciences at the University of California, Davis, led the other study.

Her team found that the brains of three-year-old boys with autism were smoother than those of typically developing peers in part of the temporal lobe.

However, the study found a change between three and five years old, with the older boys with autism showing greater folding.

Increased cortex folding in sub-group with autism

And a sub-group of autistic boys with abnormally large brains showed increased cortex folding compared to typically developing peers and other autistic boys with normal brain sizes.

Nordahl’s research measured the extent of cortex folding in 105 boys with autism and 49 typically developing boys at the ages of three and five.